What are the classifications of pressure gauges?

Classification of pressure gauges:

Pressure gauges can be divided into precision pressure gauges and general pressure gauges according to their measurement accuracy. The measurement precision/accuracy grades of the precision pressure gauge are 0.25 and 0.4 respectively; The measurement precision/accuracy grades of general pressure gauges are 1.0, 1.6, 2.5 and 4.0 respectively.

According to the nominal diameter of the casing, the commonly used pressure gauges are d40, d50, d60, d75, d100, d150, d200 and D 250 mm. 。

According to their installation methods, pressure gauges can be divided into radial direct installation, axial direct installation, radial front band installation, radial rear band installation and axial front band installation.

Pressure gauges are divided into general pressure gauges, special pressure gauges and differential pressure gauges according to their indicated pressure benchmarks. General pressure gauges are based on atmospheric pressure; The absolute pressure table is based on the low absolute pressure; A differential pressure gauge measures the difference between two measured pressures.

Pressure gauges are divided into vacuum gauge, pressure vacuum gauge gauge, micro-pressure gauge, low-pressure gauge, medium-pressure gauge and high-pressure gauge according to their measuring range. The vacuum gauge is used to measure the pressure value less than atmospheric pressure; Pressure vacuum gauge can be used to measure pressure values less than and greater than atmospheric pressure; The micro-pressure gauge is used to measure the pressure value less than 60KPa; The low pressure meter is used to measure the pressure value of 0~6MPa; The medium pressure gauge is used to measure the pressure value of 10~60MPa; The high pressure meter is used to measure the pressure above 100MPa.

Adjustment method of diaphragm pressure indication value

Diaphragm pressure gauge is a widely used pressure instrument in industry. In the verification process, the problem of indication out of tolerance is common. The specific adjustment methods are as follows:

1. The out-of-tolerance value of each verification point of diaphragm pressure gauge is the same. After boosting, the pointer can be reinstalled at the first/first verification point except the zero point to calibrate the indication.

2. The difference of diaphragm pressure gauge is linear error. When the error increases gradually, move the indicating adjusting screw outward to increase the arm length; On the contrary, it moves inward to reduce the arm length.

3. The indication of diaphragm pressure gauge is out of tolerance, which is fast first (positive error) and then slow (negative error). Turn the movement counterclockwise to enlarge the included angle between the pull rod and the sector gear; Otherwise, turn the movement clockwise to reduce the included angle. After adjustment. The error is linear, and then move the indicating adjusting screw.

diaphragm manometer

4. The indicated value of diaphragm pressure gauge is out of tolerance near half of the pressure. After boosting, the pointer can be reinstalled in the middle position. If the error cannot be eliminated, the angle between the pull rod and the sector gear should be adjusted for comprehensive adjustment.

5. Only one or two points of the diaphragm pressure gauge are out of tolerance. Check the cooperation of the movement near this point. If it is positive or negative, there is dirt and burr at the gear meshing position; When it is negative, the teeth are worn and injured and should be repaired or replaced.

6. Adjust a pressure gauge for many times, but the back-and-forth difference is still out of tolerance, and the pointer does not return to zero, so it may be that the spring tube is deformed and needs to be replaced again.

After the adjustment, assemble all parts of the instrument and re-verify it according to the verification regulations.

What are the factors that affect the use of pressure gauges?

1, the influence of freezing and vibration:

The pressure gauge is installed outside the boiler and is greatly influenced by external conditions. If the outside temperature is too low, freezing, or various vibrations from the boiler body and the inside of the pressure gauge will affect the sensitivity and accuracy of the pressure gauge pointer.

Precautions/precautions: First, install insulation devices; The second is to install a buffer device, such as the three-way cock is a shock-proof device.

2, the influence of overload:

If the elastic parts such as the spring elbow and hairspring in the pressure gauge are often in the extreme/limited or close to the extreme/limited state, the elasticity will be weakened or lost after working for a long time, and even long/long deformation will occur.

If the pointer of the pressure gauge is often at a position close to or more than 2/3 of the full scale of the dial, it is unfavorable for the long-term work of the pressure gauge.

3, the influence of temperature:

Pressure gauge is the function of pressure to deform the spring elbow. If the temperature of the medium entering the spring elbow is high, the temperature will also deform the elbow. Moreover, the high temperature medium acts on the spring elbow for a long time, which will also cause long/long deformation of the elbow. All these will adversely affect the measurement.

The preventive/preventive measures are that different forms of trap pipes are installed between the pressure gauge and the drum to store condensed water and prevent steam from directly entering the spring elbow.

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